The present invention relates to cloning a DNA coding for Achromobacter protease I (API) or variants thereof having similar activity to API, and further relates to the production of API or variants thereof using the cloned DNA segment.
API is a serine protease which was isolated from Achromobacter lyticus M497-1. API specifically cleaves the peptide bonds (--Lys--X--) at the side of the carboxyl groups of lysine residues in proteins and peptides, and is also called a lysyl end peptidase (EC 3.4.21.50). This enzyme cleaves all Lys--X bonds including the Lys--Pro bond, and therefore is very useful for the fragmentation of proteins or peptides for their primary structural analysis, in the preparation of peptide maps or in the synthesis of --Lys--X-- components.
On the other hand, the isolation and purification of proteins and polypeptides secreted by certain kinds of cells is usually very difficult, because, for example, the small amount of protein secreted. In order to solve this problem, recombinant DNA techniques have recently been employed.
The production of API has relied on the isolation of the native protein from Achromobacter lyticus. However, this natural API is isolated in very small amounts, so that there has been a desire in the art to develop a process for producing API in large amounts.